RESUMO
In the current study, we enrolled 14 Egyptian infertile males with isolated congenital bilateral absence of the vas deferens (CBAVD). Screening for the most commonly reported 36 CFTR mutations, and the intron 8 (T)n splice variant was performed by multiplex PCR followed by reversed hybridisation. Samples with the 5T variant were picked for DNA sequencing of intron 8/exon 9 region to identify the number of adjacent TG repeats. The p.Phe508del and the p.Ser1251Asn mutations were detected in heterozygous state in three patients (10.7% of alleles) and in one patient (3.6% of alleles), respectively, while the 5T variant was detected in five patients (28.6% of alleles). Among those five patients, four had TG12 repeats and one had TG13 repeats confirming the pathogenic penetrance of all 5T alleles in Egyptian CBAVD patients. The allelic frequencies of the mutations p.Phe508del, p.Ser1251Asn and the 5T variant in 60 Egyptian cystic fibrosis patients were 24.2%, 3.3% and 2.5% respectively. The mutation p.Ser1251Asn was detected for the first time in isolated CBAVD patient in our study. Due to the high prevalence of p.Phe508del mutation and 5T variant in Egyptian CBAVD patients, we recommend their screening initially, ideally followed by full CFTR gene sequencing in unidentified patients.